Where does Phlegm come from? - Naked Scientists 10.10.31

It's National Pathology Week 2010 and to celebrate the launch we're joined by pathologist Dr Suzy Lishman to take on your science questions! We'll find out where phlegm comes from, how petroleum jelly helps healing and the weight of red blood cells synthesised in a human lifetime. Also, can you concentrate lasers with lenses, why does an open carport stop frost, and if carnivorous plants photosynthesise, why do they need to eat insects? Plus, how researchers in Scotland are sniffing out pollution with such sensitivity, they can detect forest fires all the way from Canada! In Kitchen Science, Dave reads his credit card using rust!